Conventional methods for suppressing a sound in a specific area in formation of a sound field include a method of performing directivity control using a parametric speaker or a linear speaker array.
For example, there is a proposed method of local silencing by super-directivity control using a parametric speaker (refer to Non-Patent Document 1, for example). This method arranges units of the parametric speaker in the horizontal direction or physically moving or rotating the unit to enable moving an area to be silenced in the left and right directions as viewed from the speaker.
Furthermore, according to the method of performing local silencing by directivity control using a linear speaker array, it is possible to move the area to be silenced in the left and right direction as viewed from the linear speaker array by using digital signal processing.